[Ni(III)(OMe)]-mediated reductive activation of CO(2) affording a Ni(κ(1)-OCO) complex

Carbon dioxide is expected to be employed as an inexpensive and potential feedstock of C(1) sources for the mass production of valuable chemicals and fuel. Versatile chemical transformations of CO(2), i.e. insertion of CO(2) producing bicarbonate/acetate/formate, cleavage of CO(2) yielding μ-CO/μ-oxo transition-metal complexes, and electrocatalytic reduction of CO(2) affording CO/HCOOH/CH(3)OH/CH(4)/C(2)H(4)/oxalate were well documented. Herein, we report a novel pathway for the reductive activation of CO(2) by the [Ni(III)(OMe)(P(C(6)H(3)-3-SiMe(3)-2-S)(3))](–) complex, yielding the [Ni(III)(κ(1)-OCO˙(–))(P(C(6)H(3)-3-SiMe(3)-2-S)(3))](–) complex. The formation of this unusual Ni(III)(κ(1)-OCO˙(–)) complex was characterized by single-crystal X-ray diffraction, EPR, IR, SQUID, Ni/S K-edge X-ray absorption spectroscopy, and Ni valence-to-core X-ray emission spectroscopy. The inertness of the analogous complexes [Ni(III)(SPh)], [Ni(II)(CO)], and [Ni(II)(N(2)H(4))] toward CO(2), in contrast, demonstrates that the ionic [Ni(III)(OMe)] core attracts the binding of weak σ-donor CO(2) and triggers the subsequent reduction of CO(2) by the nucleophilic [OMe](–) in the immediate vicinity. This metal–ligand cooperative activation of CO(2) may open a novel pathway promoting the subsequent incorporation of CO(2) in the buildup of functionalized products.